I'm getting freezes with the ReportGPURestart message. They're pretty specific: If I open Minecraft, enter a world, and try to toggle fullscreen on or off, I am very likely to get such a crash, and if I was fullscreen, the last frame shown just stays up forever, even if other programs start and think they are displaying graphics to the screen. If I toggle fullscreen only from the settings screen while not in the game world, it seems to work fine.
MBP (classic) June 2012, 15", using an external display (so it's permanently using discrete graphics). Current minecraft, same behavior with both Java 6 and Java 7 runtimes, have updated the lightweight java game library and other bits, no change at all in behavior.
Nothing else seems to cause any problems, apple hardware test reports nothing. So basically, there exists something that Java OpenGL games can do which causes the GPU to crash, and the crash recovery is defective.